When someone uses your email account to harass you, it might fall into the category of stalking. Unlike spam emails that deluge your inbox with offers of super diets and riches from Nigeria, harassing emails are often from an estranged friend or acquaintance and at best are a form of bullying. If you dread opening your email for fear of the next attack of hateful or threatening emails, there are specific steps you can take to eliminate the problem before it escalates.
Send one reply to the person who is harassing you, saying in a firm tone that this reply constitutes an order to cease and desist. Tell them that you consider their attacks to be harassing, threatening and libelous and they are not to contact you again.
Print copies of the harassing emails and take them to your local police department. Explain that you feel threatened by the person and ask that your complaint be put on record.
Consider filing a restraint order. If the person harassing you lives in the same town, county or state, you might have legal options to get them to stop.